1. Field of the Invention
The present invention relates to a swirling device for a stirling cycle engine, and more particularly to a swirling device for producing a swirl in the air stream which is introduced into the combustion chamber of a stirling cycle engine.
2. Descriptions of Prior Art
A stirling cycle engine is a kind of external combustion engine which includes a combustion chamber for burning fuel therein to produce a heat which is used to heat a working gas through a heat exchanger. In this type of stirling cycle engine, it is essential, in accomplish an improved thermal efficiency, to improve the efficiency of combustion in the combustion chamber as well as the efficiency of the heat exchanger. In an effort to improve the efficiency of combustion, conventional stirling cycle engines include a swirling device in the passage of intake air into the combustion chamber to produce a swirl of the intake air. Known swirling devices adopted for such purposes include a swirl chamber having a plurality of substantially tangentially directed, substantially straight inlet ducts through which the intake air is drawn into the swirl chamber to produce a swirl therein. The swirling intake air is then introduced into the combustion chamber. In case where four inlet ducts are provided, these ducts are arranged perpendicular to each other.
The conventional swirling device is however disadvantageous in that the intake air stream discharged from one of the inlet ducts interfere with the intake air from another inlet duct producing a substantial pressure loss. Further, such interference weakens the swirl of the intake air and prevents uniform mixing of fuel with the intake air resulting in an incomplete combustion of fuel. It should further be noted that the inlet ducts cannot provide a sufficient passage area for the intake air so that the intake air flow speed is unavoidably increased causing a substantial friction loss. In the conventional stirling cycle engine having the aforementioned swirling device, it has been required to use a blower of a high capacity in order to compensate for the pressure loss, the incomplete combustion and the friction loss.